System and method for retransmitting packets over a network of communication channels

ABSTRACT

A system for transmitting packets over a network of communication channels, the system comprising a set of nodes comprising at least first and second nodes and a network access coordinator operative to coordinate the access of the set of nodes to a synchronous network of channels, wherein, if at least one individual packet has been transmitted from the first node to the second node which did not receive at least one packet, the second node is operative to send a retransmission request to the network access coordinator requesting retransmission of at least one individual packet.

REFERENCE TO CO-PENDING APPLICATIONS

This application claims priority as a continuation application from U.S.application Ser. No. 11/942,114, filed Nov. 19, 2007 now U.S. Pat. No.7,742,495, entitled “SYSTEM AND METHOD FOR RETRANSMITTING PACKETS OVER ANETWORK OF COMMUNICATION CHANNELS,” which is hereby incorporated byreference herein in its entirety.

This is a nonprovisional of the following U.S. Provisional applications,all of which are hereby incorporated by reference herein in theirentireties: U.S. Provisional Application No. 60/866,532, entitled, “AMETHOD FOR PACKET AGGREGATION IN A COORDINATED HOME NETWORK”, filed onNov. 20, 2006, U.S. Provisional Application No. 60/866,527, entitled,“RETRANSMISSION IN COORDINATED HOME NETWORK” filed on Nov. 20, 2006,U.S. Provisional Application No. 60/866,519, entitled, “IQ IMBALANCECORRECTION USING 2-TONE SIGNAL IN MULTI-CARRIER RECEIVERS”, filed onNov. 20, 2006, U.S. Provisional Application No. 60/907,111, “SYSTEM ANDMETHOD FOR AGGREGATION OF PACKETS FOR TRANSMISSION THROUGH ACOMMUNICATIONS NETWORK” filed on Mar. 21, 2007, U.S. ProvisionalApplication No. 60/907,126, entitled, “MAC TO PHY INTERFACE APPARATUSAND METHODS FOR TRANSMISSION OF PACKETS THROUGH A COMMUNICATIONSNETWORK”, filed on Mar. 22, 2007, U.S. Provisional Application No.60/907,819, entitled “SYSTEMS AND METHODS FOR RETRANSMITTING PACKETSOVER A NETWORK OF COMMUNICATION CHANNELS”, filed on Apr. 18, 2007, andU.S. Provisional Application No. 60/940,998, entitled “MOCAAGGREGATION”, filed on May 31, 2007.

FIELD OF THE INVENTION

The present invention relates generally to information networks andspecifically to transmitting information such as media information overcommunication lines such as coaxial conductor cables (hereinafter,“coax”).

BACKGROUND OF THE INVENTION

Home networking over coax is a known technology which has vastcommercial potential.

The Multimedia over Coax Alliance (“MoCA™”), at its websitemocalliance.org, provides an example of a suitable specification (MoCA1.0) for transmitting digital video and entertainment informationthrough coaxial cable deployed in a building, home or other structure orregion. The specification has been distributed to an open membership.

MoCA 1.0 is but one example of a suitable home networking technology.MoCA and similar technologies tap into the unused bandwidth available ondeployed coax. More than 70% of homes in the United States have deployedcoax. Many have coax in one or more primary entertainment locations,such as family rooms, media rooms and master bedrooms. MoCA or othersuitable technologies allow homeowners to utilize the coax as anetworking system and to deliver other entertainment and informationprogramming with high quality of service (“QoS”).

The technology underlying MoCA, for example, provides high speed (270mbps), high QoS, and the innate security of a shielded, wired connectioncombined with state-of-the-art packet-level encryption. Coax is designedfor carrying high bandwidth video. Today, it is regularly used tosecurely deliver millions of dollars of pay-per-view and premium videocontent on a daily basis. The MoCA network, or other similar suitablenetworks, can also be used as a backbone for multiple wireless accesspoints used to extend the reach of wireless communication throughout ahome.

MoCA, or other similar suitable technologies, can typically provide aconsistent, high throughput, high quality connection through deployedcoaxial cables to video devices in the home without affecting the analogor digital services present on the cable. MoCA provides a primary linkfor digital entertainment, and may also act in concert with other wiredand wireless networks to extend entertainment throughout the home.

MoCA works with access technologies such as ADSL and VDSL services orFiber to the Home (FTTH), that typically enter the home on a twistedpair or on an optical fiber, operating in a frequency band from a fewhundred kilohertz to 8.5 MHz for ADSL and 12 MHZ for VDSL. As servicesreach the home on via xDSL or FTTH, they may be routed via MoCAtechnology and the in-home coax to the video devices. Cablefunctionalities, such as video, voice and Internet access, may beprovided to homes, via coaxial cable, by cable operators, and usecoaxial cables running within the homes to reach individual cableservice consuming devices locating in various rooms within the home.Typically, MoCA type functionalities run in parallel with the cablefunctionalities, on different frequencies.

Coax infrastructure inside a house typically includes coaxial wires andsplitters. Splitters used in homes typically have one input and two ormore outputs and are designed to transfer signals from input to outputsin the forward direction, or from outputs to input in the backwarddirection and to isolate splitter outputs and prevent signals fromflowing room/outlet to room/outlet. Isolation is useful in order to a)reduce interference from other devices and b) maximize power transferfrom Point Of Entry (POE) to outlets for best TV reception.

The MoCA technology is specifically designed to go backwards throughsplitters (insertion) and go from splitter output to output (isolation).All outlets in a house can be reached from each other by a single“isolation jump” and a number of “insertion jumps”. Typically, isolationjumps have an attenuation of 5 to 40 dB and each insertion jumpattenuates approximately 3 dB. MoCA has a dynamic range in excess of 55dB while supporting 200 Mbps throughput. Therefore MoCA can workeffectively through a significant number of splitters.

MoCA is a managed network unlike some other home networkingtechnologies. It is specifically designed to support streaming videowithout packet loss providing very high video quality between outlets.

Digital cable programming is delivered with threshold Packet Error Rate(PER) of below 1e-6. The home network may preferably have similar orbetter performance so as not to degrade viewing.

The disclosures of any publications and patent documents mentioned inthe specification, and of the publications and patent documents citedtherein directly or indirectly, are hereby incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features of the present invention, its nature andvarious advantages will be more apparent upon consideration of thefollowing detailed description, taken in conjunction with theaccompanying drawings, and in which:

FIG. 1 is a prior art timing diagram;

FIG. 2 is an illustrative timing diagram in accordance with theprinciples of the invention;

FIG. 3 is another illustrative timing diagram in accordance with theprinciples of the invention;

FIG. 4 is yet another illustrative timing diagram in accordance with theprinciples of the invention;

FIG. 5 is still another illustrative timing diagram in accordance withthe principles of the invention;

FIG. 6 is another illustrative timing diagram in accordance with theprinciples of the invention;

FIG. 7 is an illustrative timing diagram in accordance with theprinciples of the invention;

FIG. 8 is another illustrative timing diagram in accordance with theprinciples of the invention; and

FIG. 9 is an illustrative timing diagram in accordance with theprinciples of the invention.

FIG. 10 shows schematically an illustrative device that may be used inaccordance with the principles of the invention.

FIG. 11 shows an illustrative home network system in accordance with theprinciples of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention provides improved systems and methods forstreaming media over coax.

Some embodiments of the invention may include a system for transmittingpackets over a network of communication channels. The system may includea set of nodes comprising at least first and second nodes and a networkaccess coordinator operative to coordinate the access of the set ofnodes to a synchronous network of channels, wherein, if at least oneindividual packet has been transmitted from the first node to the secondnode which did not receive at least one packet, the second node isoperative to send a retransmission request to the network accesscoordinator requesting retransmission of at least one individual packet.

The network may have a Coordinated MAC to allow contention free access.The coordinated MAC may be a home network coordinated MAC such as, forexample, that described in the MoCA MAC/PHY SPECIFICATION v. 1.0 (“theMoCA Specification”), Feb. 22, 2006, which is hereby incorporated hereinin its entirety. The MoCA Specification identifies features of a homenetwork over existing coaxial cable. The method may allow the expansionof the coordinated network MAC to other media in the home like powerlines and phone lines (or wireless) to improve the accessibility of thenetwork to rooms in the home that are not accessible via coaxial cables.

The retransmission request for an individual packet which failed totransmit in MAP cycle N may occur in MAP cycle N+1.

The network access coordinator may be operative to receive and to accedeto the retransmission request.

The retransmission of an individual packet which failed to transmit inMAP cycle N may occur in MAP cycle N+2.

Some embodiments of the invention may include a system for transmittingpackets over a network of communication channels. The system may includea set of nodes interconnected by a synchronous network of channels and anetwork access coordinator operative to coordinate the access of the setof nodes to the synchronous network of channels including providing aplurality of slots in each MAP cycle for packet transmission requestssent to the coordinator by individual nodes in the set of nodes, andwherein at least one individual node in the set of nodes is operative toutilize an individual slot from among the plurality of slots to transmitto the coordinator both a reservation request and a retransmissionrequest, the reservation request including a request to transmit a firstpacket to a first additional node and the retransmission requestincluding a request that a second additional node retransmit a secondpacket previously unsuccessfully transmitted from the second additionalnode to the individual node.

In some embodiments, the network access coordinator may be operative toprovide a plurality of slots in each MAP cycle for packet transmissionrequests sent to the coordinator by individual nodes in the set ofnodes. At least one individual node in the set of nodes may be operativeto utilize an individual slot from among the plurality of slots totransmit to the coordinator both a reservation request and aretransmission request, the reservation request including a request totransmit a first packet to a first additional node and theretransmission request including a request that a second additional noderetransmit a second packet previously unsuccessfully transmitted fromthe second additional node to the individual node.

In some embodiments, if a plurality of packets have been transmittedfrom the first node to the second node which did not receive at leastsome of the plurality of packets, the second node may be operative tosend a single burst to the network access coordinator. The burst mayinclude retransmission requests requesting retransmission of thosepackets from among the plurality of packets which were not received.

In some embodiments, a retransmission request sent by the second node ina MAP cycle N may requests retransmission of only those packets whichwere not received by the second node in a previous MAP cycle N−1.

In some embodiments, overhead information which is common to thereservation request and the re-transmission request may be transmittedby the individual node to the coordinator only once.

In some embodiments, if the first node sent the second node, in a MAPcycle N1, an aggregation frame including a plurality of packets onlysome of which were received by the second node, in MAP cycle N, thesecond node may refrain from requesting retransmission of those packets,from among those sent in MAP cycle N−1, which were successfully receivedand successfully de-aggregated by the second node.

In some embodiments, at least one retransmission request may include anindication of a slot duration to be used to retransmit the individualpacket.

In some embodiments, if the first node sent the second node, in a MAPcycle N−1, an aggregation frame including a plurality of packets onlysome of which were received by the second node, the retransmissionrequest sent by the second node to the network access coordinator mayrequest retransmission of less than all of the plurality of packets andmay include an indication, computed by the second node, of a slotduration to be used to retransmit the packets for which retransmissionis requested.

In some embodiments, a retransmission request sent by the individualnode in a MAP cycle N requests retransmission of only those packetswhich were not received by the individual node in a previous MAP cycleN−1.

In some embodiments, if in a MAP cycle N−1, the second additional nodesent the individual node an aggregation frame including a plurality ofpackets, only some of which were received by the individual node, in MAPcycle N, the individual node may refrain from requesting retransmissionof those packets, from among those sent in MAP cycle N−1, which weresuccessfully received and successfully de-aggregated by the individualnode.

In some embodiments, if in a MAP cycle N−1, the second additional nodesent the individual node an aggregation frame including a plurality ofpackets only some of which were received by the individual node, theretransmission request sent by the individual node to the network accesscoordinator may request retransmission of less than all of the pluralityof packets and may include an indication, computed by the individualnode, of a slot duration to be used to retransmit the packets for whichretransmission is requested.

Some embodiments of the invention may include a method for transmittingpackets over a network of communication channels. The method may includecoordinating the access of a set of nodes to a synchronous network ofchannels interconnecting the set of nodes. The coordinating may includeproviding a plurality of slots in each MAP cycle for packet transmissionrequests sent to a coordinator by individual nodes in the set of nodes.In some embodiments, at least one individual node in the set of nodesmay be operative to utilize an individual slot from among the pluralityof slots to transmit to the coordinator both a reservation request and aretransmission request, the reservation request including a request totransmit a first packet to a first additional node and theretransmission request including a request that a second additional noderetransmit a second packet previously unsuccessfully transmitted fromthe second additional node to the individual node.

Some embodiments may include a method for transmitting packets over anetwork of communication channels. The method may include coordinatingthe access of a set of nodes, which may include at least first andsecond nodes, to a synchronous network of channels interconnecting theset of nodes. In some embodiments, if at least one individual packet hasbeen transmitted from the first node to the second node which did notreceive at least one packet, the second node may be operative to send aretransmission request to a network access coordinator requestingretransmission of at least one individual packet.

Typically, as a result of the de-aggregation process, the Rx node knowsthe size of a frame since size information is included in the frame'sheader. The Rx node may know some or all of the sizes of the individualpackets in the frame either because this information was included inpacket headers, and the packet headers were received even if theirassociated packets were not, or because the information regarding sizesof packets was included in the frame header. If a particular packet sizeis not known, the Rx node typically requests that all packets from thatpacket onward be re-transmitted. If all packet sizes are known, the Rxtypically requests re-transmission only of missing packets and easilyindicates a suitable slot duration as the sum of the known sizes of allmissing packets.

Positive or Negative Acknowledgements for properly received packets aretypically effected via the Reservation Request messages from thereceiving node to the network coordinator.

An acknowledgment message (“ACK”) is typically a single messagereferring to a burst of received packets. In the context of packetaggregation distinct negative acknowledgment messages (“NACKs”)typically correspond to individual packets in the aggregated receivedburst.

The network coordinator may include an Automatic Retransmission request(“ARQ”) mechanism. If so, it may be used as a proxy to convey one ormore ACK messages to the transmitting node and to retransmit one or moreimproperly received packets. The ARQ mechanism typically does notrequire additional bandwidth, in contrast to conventional retransmissionmechanisms.

Some embodiments of the invention may include a method forretransmitting a packet before initial transmission of a next-queuedpacket. Packet order is thus retained by not transmitting thenext-queued packet before receiving an acknowledgement of thealready-transmitted packet.

Table 1 lists abbreviations that are used in the description and FIGS.herein.

TABLE 1 Acronym Term RP Retransmission Protocol R-ACK ReceiptAcknowledgement RTR Retransmission Request RQ-T Retransmission RequestTransmitter RQ-S Retransmission Request Signal RQ-C RetransmissionRequest Coordinator ARQ Automatic Retransmission request MAP MediumAccess Plan ACK Acknowledgment Message NACK Negative AcknowledgmentMessage RR Retransmission Request P#Z Packet No. Z X→Y Information beingtransmitted from Node X to Node Y

FIG. 1 shows a timing diagram corresponding to one example of a MACaccess method for an illustrative coordinated network. A networkcoordinator controls access to network media by allocating transmissionopportunities to all network terminals. The coordinator thereby reducesor eliminates the likelihood that there will be contention in thenetwork. The coordinator may assign priorities to the transmission ofinformation based on information source, content, affect on QoS or anyother suitable criterion. Some coordinated networks have collision-freeperiods as well as collision periods. Others, such as those governed bythe MoCA Specification, have only collision free periods.

One prior art MAC Access Method is described in the MoCA MAC/PHYSPECIFICATION v1.0, Feb. 22, 2006. FIG. 1 shows the MoCA MAC schema forcoordination of network access by a network coordinator. The access timeis divided into MAP cycles which are managed by the network coordinator.Access rules for a MAP cycle may be defined in a MAP message sent in aprevious MAP cycle by the network coordinator to all nodes.

The FIG. 1 example includes three network nodes: coordinator, node 1 andnode 2. The coordinator sends transmission opportunities for MAP cycle Nin the MAP message of the MAP cycle N−1. Illustrative opportunities andsome corresponding illustrative precedents that may be associated withthe timing diagram of FIG. 1 are summarized in Table 2.

TABLE 2 Opportunity number Opportunity Precedent 1 Reservation request(“RR”) for node #1 2 RR for node #2 3 First data packet transmittedBased on a MAP cycle N − 1 by node #1 to node #2 node # 1 requestgranted in the MAP message of that cycle by the coordinator. 4 Secondpacket transmitted by node #1 to node #2 5 MAP message for cycle Basedon RR received N + 1 (sent by coordinator) Opportunities Nos. 1 and 2. 6Data transmitted from node #2 to coordinator 7 Third data packettransmitted by node #1 to node #2 8 Data transmitted from coordinator tonode #1 9 Extension packet May be included if the data in opportunity 9is less than a minimum burst size.

Typically, there is an Inter Frame Gap (IFG) between any two burststransmitted, and there is a minimum burst size. If data size is smallerthan the Min Burst Size an extension packet size may be allocated asshown in FIG. 1.

The IFG as well as the Min Burst Size typically cause additionaloverhead and reduce the effective data rate of the network, however,they contribute toward reliable operation of the modem.

Retransmission is useful for increasing the robustness of datatransfers, because a packet that was received with an error can beretransmitted. In particular, retransmissions are common in media thatare susceptible to impulse noises. Impulse noises are created by homeappliances as well as other noise sources and are received on wiredmedia such as phone lines and power lines. Other media, such as EthernetCATS wires and coaxial wires, are much less susceptible to impulsenoises due to their better isolation from external noises. An impulsenoise can be high enough in amplitude and long enough in time to causepacket errors or even packet loss.

If a coordinated network is to operate over noisy media (such astelephone lines or power lines) a Retransmission Protocol (“RP”) istypically employed to provide appropriate network performance. Thecoordinated network shown in FIG. 1 is designed to operate over “quiet”media. An example of a network designed to provide a robust and reliablehome networking over coaxial cables is that described the MoCASpecification. Embodiments of the invention may include providing an RPin connection with a coordinated network protocol, such as that setforth in the MoCA Specification. The methods described herein may beused efficiently in conjunction with the MoCA Specification in othersuitable media, such as power lines and phone lines.

In some embodiments of the invention, the network coordinator may selectfrom several retransmission protocols. One protocol may be set as adefault method that is implemented by all nodes. A general algorithm foran RP is as follows:

1. The transmitting node transmits a packet or several packets and waitsfor an acknowledgement;

2. A. If the receiving node receives the packet correctly, the receivingnode sends a Receive Acknowledgement (R-ACK).

B. If the receiving node does not receive the packet correctly, thereceiving node sends a Retransmission Request (RTR).

3. The transmitting node, upon receiving an R-ACK or RTR, retransmitsthe packet.

4. The transmitting node retransmits the package if neither an R-ACK norRTR were sent.

The maximum number of retransmissions is typically a parameter of a datastream. The stream may include video data. The stream may include voicedata. The stream may include browsing data. The stream may include anysuitable type of data. After the transmitting node has sent the maximumnumber of retransmissions, no further attempts to transmit the packetare made. The receiving node typically forwards the received packets inthe order of transmission by the transmitting node. If a packet ismissing, the receiver node typically does not forward the next packetuntil the missing packet is received unless the maximum number ofretransmissions has been reached.

Five illustrative ARQ protocol-based methods, and three more generalretransmission methods based thereupon, are now described. In someembodiments of the invention, nodes may select an ARQ protocol duringthe establishment of a connection. One of the options is typically setas a default method that is implemented by all nodes. For example,Method #1 can be the default method. In general, ARQ protocols follow analgorithm such as:

1. The transmitting node sends a reservation request (“RR”)corresponding to an expected transmission of a packet. If ARQ isemployed, the node so signifies in the RR.

2. The transmitting node transmits the packet and waits for an ACK.

3. The receiving node receives the packet and checks if it has beenreceived correctly.

4. If the packet has been received correctly the receiving network sendsan ACK.

5. If the packet has been received incorrectly, or not at all, thereceiving node either sends a NACK or does not reply.

6. Upon receiving an ACK or a NACK, the transmitting node decideswhether to retransmit the packet or not. If neither ACK nor NACK werereceived the transmitted node may retransmit the packet.

7. The number of retransmissions is a parameter of the connection.

FIG. 2 shows illustrative method 1 (Immediate ARQ), which may includesome or all of the following steps in a suitable order:

1. The transmitting (TX) node in its reservation request (RR) requeststo transmit a packet to the receiving node indicating that transmissionis under ARQ.

2. The coordinator allocates two time slots for the transmission of thispacket. The first slot is for transmission of the packet by the TX node.The second slot is for transmission of the ACK/NACK message by thereceiving (RX) node immediately following the TX. In some embodiments,the coordinator allocates slots that are equal to a minimum burst size.3. The TX node sends the packet after the TX node receives a grantmessage indicating that coordinator granted a RR for the packet.4. The RX node sends the ACK/NACK in the second slot.5. The TX analyzes the ACK/NACK message and, if NACK is received, in thenext RR opportunity the TX node request for retransmission the packet.6. The coordinator receives the RR and grants the request if the maximumnumber of retransmission requests has not yet been reached.7. If granted, the TX node retransmits the packet in the next MAP cycle.8. This procedure can repeat itself several times according to theparameters of the ARQ of this connection.

FIG. 3 shows illustrative method 2 (Single Frame ARQ), which may besimilar to method 1 (shown in FIG. 2), except that the allocation forthe ACK/NACK message does not necessarily immediately follow the TX nodetransmission.

FIG. 4 shows illustrative method 3 (Multiple Frame ARQ), which may besimilar to method 2, except that one ACK/NACK is sent to acknowledge inaggregate more than one received packet. For example, FIG. 4 shows anACK for packet 2 and a NACK for packet 3.

FIG. 5 shows illustrative method 4 (ACK/NACK Embedded in RR—included inARQ messages) enables more efficient ARQ throughput. The ACK/NACKmessage is not transmitted on its own and instead is embedded in the RRmessage of the RX node in MAP cycle N+1. When RR messages are shorterthan the Min Burst Size time, additional overhead for the ACK/NACK maybe conserved (although higher latency may be involved).

FIG. 6 shows illustrative method 5 (Very short Immediate ACK/NACK),which may be similar to Method 1, except that the ACK/NACK is a veryshort message, such as a 64 bit BPSK series that is detected by the PHY.This is efficient with respect to throughput, but may require changes tothe PHY and fast response to detection of error (or no error) bytransmission of the short ACK/NACK.

FIG. 7 shows illustrative method 6 (Retransmission Request Transmitter(RQ-T)), which may be operative to send single or burst R-ACK/RTRmessage to the transmitter. In some embodiments of the invention, themethod may include some or all of the following steps in a suitableorder such as the following:

1. The transmitting (TX) node in its reservation request (RR) requeststo transmit one or multiple frames to the receiving node.

2. The transmitting node indicates in the RR the following information:

A. An indication that the frame is in Retransmission Protocol;

B. An indication that the method of RP is preferred over RQ-T; and

C. Single or burst RQ-T.

3. The coordinator allocates slots for the transmission and RP of theframes typically in one of the following orders:

A. If single RQ-T is used, a slot is allocated for transmission of thefirst frame by the TX node, a slot is then allocated for transmission ofthe single RQ-T message by the RX node, and finally, slots are allocatedfor the rest of the frames deemed “required” by the TX node.

B. If a burst of RQ-T is used, slots are allocated for transmission ofall frames deemed “required” by the TX node, and one slot is thenallocated for transmission of the burst RQ-T message by the RX node.

3.1 In some embodiments, the coordinator may be operative to allocateone or more slots for an RQ-T message immediately after a packet orpackets that required RQ-T or in a corresponding or subsequent MAP.

4. The coordinator indicates to the RX node which frames are to beacknowledged in each RQ-T message.

5. The TX node sends the frames according to the grant received from thecoordinator.

6. The RX node sends an RQ-T message in the RQ-T slots granted by thecoordinator.

7. The RQ-T message is sent, with an indication of R-ACK or RTR, forframes that requested acknowledgment in that specific RQ-T message.

8. The TX node analyzes the RQ-T message and may, ifapplication-appropriate, add an RR element in the next RR transmissionfor retransmission of the frames missed by the RX node.

9. The coordinator receives the RR and may grant the slot according tothe above steps.

10. The foregoing actions may be repeated several times, provided thatthe maximum number of retransmissions is not exceeded.

FIG. 8 shows illustrative method 7 (Retransmission Request Signal(RQ-S)), which may be operative to send single R-ACK1RTR signal to thetransmitter. In some embodiments, the RQ-S may include a short signalwith an indication of R-ACK or RTR which may be allocated immediatelyfollowing each burst requiring retransmission under the RQ-S method.Method 7 typically comprises some or all of the following steps in asuitable order such as the following:

1. The transmitting (TX) node in its reservation request (RR) requeststo transmit one or multiple of frames to the receiving node.

2. The transmitting node indicates in the RR the following information:

A. An indication that the frame is in Retransmission Protocol; and

B. An indication that the RP method is preferred over the RQ-S method.

3. The coordinator allocates, for each burst with RQ-S, the slot fortransmission of the frame by the TX node and the slot for transmissionof the RQ-S signal by the RX node.

4. The coordinator and the RX node check whether the RQ-S signal bearsan indication of R-ACK or RTR.

5. If the RQ-S indicates R-ACK, the TX node clears the packet.

6. If the RQ-S indicates RTR, the coordinator allocates a slot forretransmission of the frame by the TX node.

7. If the coordinator has not received the RQ-S and the TX node receivesit with R-ACK, the coordinator allocates a slot for retransmission andthe TX node sends an empty frame.

8. If the TX node has not received the RQ-S and the coordinator receivesit with an R-ACK indication, the coordinator indicates that the framewas received correctly in the next allocation slot of the flow.

9. The R-ACK or RTR indication is on the whole frame with no indicationper packet if the frame is aggregate.

A short RQ-S signal is easy to distinguish from other network signals. Ashort RQ-S may use a commonly known (MoCA, e.g.) PHY preamble used bythe network with different parameters. For example, an RQ-S with R-ACKindication may comprise 8 S signals followed by 4 L2 series followed byan inverted 4 L2 series followed by an S quiet period and two L1sequences. An RQ-S with RTR indication may comprise 8 S signals followedby 4 L2 series followed by inverted 4 L2 series followed by an S quietperiod and two L4 sequences, such as that shown below.

S = {0, 1, 1, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 1, 1, 1, 1, 1, 0}L 4 = {1, 0, 0, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 0, 0, 1, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 1, 1, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 1}L 2 = {1, 0, 1, 1, 1, 0, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1, 0, 0, 0, 1, 1, 1, 0, 1, 0, 0, 0, 0, 1, 1, 0, 1}L 1 = {0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1, 0, 0, 0, 1, 1, 1, 0, 1, 0, 0, 0, 0, 1, 1, 0, 1, 0, 1, 1, 1, 0, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0}

FIG. 9 shows illustrative method 8 (Retransmission Request Coordinator(RQ-C)), which may be operative to send burst R-ACK or RTR to thenetwork coordinator. In some embodiments, the acknowledgement indicationis typically sent to the coordinator in the Reservation Request Message.The method typically comprises some or all of the following steps in asuitable order such as the following:

1. The transmitting (TX) node in its reservation request (RR) requeststo transmit one or multiple frames to the receiving node.

2. The transmitting node indicates in the RR the following information:

A. That the frame is in Retransmission Protocol; and

B. That the method of RP is preferred over RQ-C.

3. The coordinator allocates slots for transmission of the frames by theTX node.

4. In the next MAP cycle the coordinator allocates an RR slot for the RXnode (even if the RX node does not need an RR slot for its TX frames).

5. The RX node checks which frame s were received correctly and whichwere not, from all TX nodes sent to it in the previous MAP cycle.

6. The RX node sends, in the RR message, an R-ACK or RTR indication forall frames which employ RQ-C.

7. The RTR is typically sent with some or all of the followinginformation:

A. The sequence of frame s for retransmission;

B. If the frame was an aggregation frame and a portion of its packetswas received incorrectly, send the packet sequence of the missedpackets;

C. The durations used for retransmission of these frames. If the wholeframe is to be retransmitted, the duration may be taken from the RX dataslot, whereas if only a portion of the frame is to be retransmitted, theduration may be computed according to the PHY profile of the TX and RXnodes.

8. In the next MAP cycle, the coordinator allocates slots to be used bythe RX node for retransmission of the frames by the TX node.

9. If the R-ACK for some frames is sent in the RR message, thecoordinator indicates in the next MAP that these frames were receivedcorrectly.

10. The TX node receives a MAP with slots for retransmission of the lostframes/packets and with an indication of which frames/packets werereceived correctly by the RX node.

11. The TX node clears frames/packets received correctly and retransmitslost frames/packet.

12. The RX node may re-send RTR for a specific frame/packet until alimit on the number of retransmissions is reached.

13. if the limit is reached, the frame/packet may still not have beenreceived.

Methods 6 or 8 may be usable for high bit rate stream such as HD video.

Method 7 may be usable for low bit rate stream such as voice in whichthe RX node is only a listener. This method may reduce bandwidth whenthe RR is allocated infrequently or not at all for the TX or RX nodes.The RR is not allocated to the TX node when the stream is sent in anunsolicited manner.

Method 8 may save bandwidth for RP by merging the RP in the RR slots. Tothe extent that the RX node receives streams in RP, the saved timeincreases.

FIG. 10 shows a single or multi-chip module 1002 according to theinvention, which can be one or more integrated circuits, in anillustrative data processing system 1000 according to the invention.Data processing system 1000 may include one or more of the followingcomponents: I/O circuitry 1004, peripheral devices 1006, processor 1008and memory 1010. These components may be coupled together by a systembus or other interconnections 1012 and are disposed on a circuit board1020 in an end-user system 1030 that may be in communication with a coaxmedium transmitting packets in accordance with the systems and methodsdiscussed above.

FIG. 11 is a simplified block diagram illustration of a home networksystem 1102 that uses a coax backbone 1105. The home network system 1102of FIG. 11 is operative for transmitting packets over coax backbone 1105within a home 1100. The home network system 1102 includes first node1110, second node 1120 and network access coordinator 1115. First node1110, second node 1120 and network access coordinator 1115 areconfigured to communicate over coax backbone 1105.

It is appreciated that for clarity the description throughout thespecification, including specific examples of parameter values providedherein, is sometimes specific to certain protocols such as the MoCAand/or Ethernet protocols however, this is not intended to be limitingand the invention may be suitably generalized to other cable protocolsand/or other packet protocols. For example, use of terms, such as Map,Allocation Unit, Reservation Request etc. which may be specific to aparticular protocol such as MoCA or Ethernet, to describe a particularfeature or embodiment is not intended to limit the scope of that featureor embodiment to that protocol specifically; instead the terms are usedgenerally and are each intended to include parallel and similar termsdefined under other protocols.

It is appreciated that software components of the present inventionincluding programs and data may, if desired, be implemented in ROM (readonly memory) form including CD-ROMs, EPROMs and EEPROMs, or may bestored in any other suitable computer-readable medium such as but notlimited to disks of various kinds, cards of various kinds and RAMs.Components described herein as software may, alternatively, beimplemented wholly or partly in hardware, if desired, using conventionaltechniques.

Features of the present invention which are described in the context ofseparate embodiments may also be provided in combination in a singleembodiment. Conversely, features of the invention which are describedfor brevity in the context of a single embodiment may be providedseparately or in any suitable subcombination.

1. A home network system for transmitting packets over a network ofcommunication channels, the system comprising: first and second nodes incommunication with a coax backbone, the coax backbone being locatedwithin a home; and a network access coordinator operative to coordinateaccess of the nodes to the coax backbone, the network access coordinatorbeing located within the home; wherein, if in a time period at least onefirst packet is transmitted by the first node to the second node, but isnot received by the second node, the second node is operative to send aretransmission request to the network access coordinator, the requestrequesting packet retransmission; wherein the network access coordinatoris operative to: receive the request; and accede to the request.
 2. Thesystem of claim 1 wherein, when the time period is Media Access Plan(MAP) cycle n, the request occurs in MAP cycle n+1.
 3. The system ofclaim 2 and wherein the first code is operative to retransmit the packetin MAP cycle n+2.
 4. The system of claim 1 wherein: the time period is aMedia Access Plan (MAP) cycle; the network access coordinator isoperative to provide in a cycle a slot for packet transmission requests;and the first node is operative to utilize the slot to transmit to thecoordinator: a first request to transmit a packet to the second node;and a second request that a third node retransmit a packet.
 5. Thesystem of claim 1 wherein, when the at least one packet is a pluralityof packets, the second node is operative to send a single burst to thenetwork access coordinator, the burst including retransmission requestscorresponding to each of the packets in the plurality.
 6. The system ofclaim 1 wherein: if the time period is Media Access Plan (MAP) cyclen−1; and in the cycle at least one second packet is transmitted by thefirst node to the second node, and is received by the second node, theretransmission request: is sent in MAP cycle n; and requestsretransmission of only the first packet.
 7. The system of claim 1wherein: the time period is Media Access Plan (MAP) cycle n−1; in thecycle at least one second packet is transmitted by the first node to thesecond node, and is received by the second node; the first and secondpackets are included in an aggregation frame; the second packet issuccessfully deaggregated; and the retransmission request is: sent inMAP cycle n+1; and does not request retransmission of the second packet.8. The system of claim 1 wherein the retransmission request comprises aslot duration to be used to retransmit a first packet.
 9. The system ofclaim 8 wherein the slot duration is computed by the first node.
 10. Thesystem of claim 1 wherein the retransmission request comprises a slotduration to be used to retransmit more than one first packet.
 11. Thesystem of claim 1 wherein the retransmission request comprises a slotduration to be used to retransmit all first packets.
 12. A home networksystem for transmitting packets over a network of communicationchannels, the system comprising: first, second and third nodes incommunication with a coax backbone, said first, second and third nodesbeing located in a home; a network access coordinator in communicationwith the coax backbone, the coordinator located in the home, thecoordinator operative to: coordinate access of the nodes to the coaxbackbone; and provide a request slot in a Media Access Plan (MAP) cycle;wherein the first node is operative to utilize the slot to transmit tothe coordinator; a first request to transmit a packet to the secondnode; and a second request that the third node retransmit a packet. 13.The system of claim 12 wherein, when there is information that is commonto the first and second requests, the first node is operative totransmit the information only once.
 14. The system of claim 12 wherein,when in MAP cycle n−1: (a) at least one first packet is transmitted bythe third node to the first node, but is not received by the secondnode; and (b) at least one second packet is transmitted by the firstnode to the second node, and is received by the second node; and thesecond request: is sent in MAP cycle q and requests retransmission ofonly the first packet.
 15. The system of claim 12 wherein: the first andsecond packets are included in an aggregation frame; the second packetis successfully deaggregated; and the second request does not requestretransmission of the second packet.
 16. The system of claim 12 wherein:the second request comprises a slot duration to be used, to retransmit afirst packet.
 17. The system of claim 16 wherein the slot duration iscomputed by the first node.
 18. The system of claim 12 wherein thesecond request comprises a slot duration to be used to retransmit morethan one first packet.
 19. The system of claim 12 wherein the secondrequest comprises a slot duration to be used to retransmit all firstpackets.
 20. A method for transmitting packets over a coax backbonelocated in a home, the method comprising: providing a plurality of slotsin a Media Access Plan (MAP) cycle for packet transmission requests sentto a coordinator by a first node in communication with the coaxbackbone, the node being operative to utilize at least one of the slotsto transmit to the coordinator both a reservation request and aretransmission request, the reservation request including a request totransmit a first packet to a second node and the retransmission requestincluding a request that a third node retransmit a second packetpreviously unsuccessfully transmitted from said third node to said firstnode.
 21. One or more non-transitory computer-readable media storingcomputer-executable instructions which, when executed by a processor ona computer system, perform a method for transmitting packets over a homenetwork of communication channels, the method comprising: communicatingbetween a first node and a second node via a coax backbone, the firstnode, the second node and the coax backbone being located within a home;coordinating access to the coax backbone using a network accesscoordinator, the network access coordinator being located within thehome; and if in a time period at least one first packet is transmittedby the first node to the second node, but is not received by the secondnode, operating the second node to send a retransmission request to thenetwork access coordinator, the request requesting packetretransmission; operating the network access coordinator to: receive therequest; and accede to the request.
 22. The non-transitory media ofclaim 21, wherein, when the time period is Media Access Plan (MAP) cyclen, the method further comprising operating the second node to send therequest in MAP cycle n+1.
 23. The non-transitory media of claim 22, themethod further comprising, operating the network access coordinator to:receive the request; and accede to the request.
 24. The non-transitorymedia of claim 22, the method further comprising operating the firstnode to retransmit the packet in MAP cycle n+2.
 25. The non-transitorymedia of claim 21, wherein: the time period is a Media Access Plan (MAP)cycle; the network access coordinator is operative to provide in a cyclea slot for packet transmission requests; and the first node is operativeto utilize the slot to transmit to the coordinator: a first request totransmit a packet to the second node; and a second request that a thirdnode retransmit a packet.
 26. The non-transitory media of claim 21,wherein, when the at least one packet is a plurality of packets, themethod further comprising operating the second node to send a singleburst to the network access coordinator, the burst includingretransmission requests corresponding to each of the packets in theplurality.
 27. The non-transitory media of claim 21, wherein: if thetime period is Media Access Plan (MAP) cycle n−1; and in the cycle atleast one second packet is transmitted by the first node to the secondnode, and is received by the second node, sending the retransmissionrequest is sent in MAP cycle n and requesting retransmission of only thefirst packet.
 28. The non-transitory media of claim 21, wherein: thetime period is Media Access Plan (MAP) cycle n−1; in the cycle at leastone second packet is transmitted by the first node to the second node,and is received by the second node; the first and second packets areincluded in an aggregation frame; the second packet is successfullydeaggregated; and the retransmission request is: sent in MAP cycle n+1;and does not request retransmission of the second packet.
 29. Thenon-transitory media of claim 21, wherein the retransmission requestcomprises a slot duration to be used to retransmit a first packet. 30.The non-transitory media of claim 29, wherein the slot duration iscomputed by the first node.
 31. The non-transitory media of claim 21,wherein the retransmission request comprises a slot duration to be usedto retransmit more than one first packet.
 32. The non-transitory mediaof claim 21, wherein the retransmission request comprises a slotduration to be used to retransmit all first packets.